Thermal transfer layer

Abstract

PCT No. PCT/FR87/00220 Sec. 371 Date Feb. 12, 1988 Sec. 102(e) Date Feb. 12, 1988 PCT Filed Jun. 15, 1987 PCT Pub. No. WO87/07695 PCT Pub. Date Dec. 17, 1987.The invention concerns a thermal transfer layer with high transfer coefficient between two materials which can have different expansion coefficients. The thermal transfer layer comprises expanded graphite inserted between the materials which are selected from among carbonaceous materials, ceramics and metals or metal alloys. The expanded graphite is either inserted in the form of a rolled or compressed sheet, or is compressed in situ. The invention also concerns a device for the cooling of a structure subjected to intense, continuous, intermittent or pulsating heat flux, by means of fluid circulation tubes placed in the passages in the structure. A flexible material which is a good heat conductor in a compressed state, such as expanded graphite, is placed between the structure to be cooled and each tube.

What is claimed is: 
     
       1. In a structure subjected to an intense continuous, intermittent or pulsating heat flux, a cooling means comprising fluids circulation tubes placed in passages in said structure, each of said tubes being surrounded by a layer of a heat conducting flexible carbonaceous material compressed between said tube and said structure, the heat transfer coefficient between said tube and said structure being at least 10 4  Wm -2  K -1 . 
     
     
       2. Structure as in claim 1, wherein said fluid circulation tubes are metallic. 
     
     
       3. Structure as in claim 1 or 2 wherein the flexible material 4 comprises expanded graphite. 
     
     
       4. Structure as in claim 3, wherein the expanded graphite is charged with a metal powder. 
     
     
       5. Structure as in claim 1 or 2 wherein the flexible carbonaceous material 4 is selected from the group consisting of woven materials and felts of carbon fibers and graphite. 
     
     
       6. Structure as in claim 5, wherein said fibrous carbonaceous material is charged with metal powder. 
     
     
       7. Process for fabricating a cooling device for a structure comprising a plurality of passages which is subjected to an intense continuous, intermittent or pulsating heat flux, comprising the steps of: (a) surrounding each of a plurality of fluid circulation tubes with a layer of heat conducting, flexible material;   (b) inserting each said surrounded tube into a passage in said structure; and   (c) subsequently subjecting each said surrounded tube to an expansion under pressure sufficient to cause each layer of said flexible material to be compressed between said structure and the corresponding tube with a force of at least 10 kPa.   
     
     
       8. Process for fabricating a cooling device for a structure comprising a plurality of discrete elements which is subjected to intense continuous, intermittent or pulsating heat flux, comprising the steps of: (a) forming at least one semicircular passage in a surface of each of said elements;   (b) lining each said passage with a flexible, heat conducting material;   (c) nesting a cooling tube in each said liquid passage; and   (d) joining said elements and tubes so as to place said heat conducting material under a compressive force of at least 10 kPa.   
     
     
       9. Process as in claim 7 or 8, wherein the flexible material 4 is expanded graphite. 
     
     
       10. Process as in claim 9, wherein the expanded graphite is charged with a metal powder. 
     
     
       11. Process as in claim 7 or 8, wherein the flexible material 4 comprises a fibrous carbonaceous material selected from the group consisting of woven materials and felts of carbon fibers and graphite. 
     
     
       12. Process as in claim 11, wherein said fibrous carbonaceous material is charged with metal powder. 
     
     
       13. Process as in claim 8 or 8, wherein said structure being cooled is a wall of a thermonuclear fusion reactor.